Functional interaction between the ZO-1-interacting transcription factor ZONAB/DbpA and the RNA processing factor symplekin
Functional interaction between the ZO-1-interacting transcription factor ZONAB/DbpA and the RNA processing factor symplekin
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DOI：
10.1242/jcs.03297
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发表时间：
2006-12-15
影响因子：
4
通讯作者：
Matter, Karl
中科院分区：
文献类型：
--
作者：
Kavanagh, Emma;Buchert, Michael;Matter, Karl
上皮紧密连接通过控制与连接组分相互作用的转录因子的活性参与基因表达的调节。一种这样的蛋白质是Y盒转录因子ZONAB/DbpA，其结合到ZO-1，连接斑的组分。Symplekin是另一种与紧密连接相关的核蛋白，其功能是调节多聚腺苷酸化，从而促进基因表达。在这里，我们解决了这两种蛋白质是否相互作用以及这是否具有功能相关性的问题。我们证明，ZONAB/DbpA和symplekin形成一个复杂的肾脏和肠上皮细胞，可以免疫沉淀，并存在于细胞核中。ZONAB/DbpA和symplekin之间的相互作用可以用重组蛋白重建。在ZONAB/DbpA作为阻遏物发挥功能的报告基因测定中，symplekin与ZONAB/DbpA在功能上相互作用，表明symplekin也可以促进转录阻遏。RNAi实验表明，symplekin耗竭降低了结肠腺癌细胞中ZONAB/DbpA的核积累和转录活性，导致增殖抑制和ZONAB/DbpA靶基因细胞周期蛋白D1的表达降低。因此，我们的数据表明，symplekin和ZONAB/DbpA合作的转录调节，并促进上皮细胞增殖和细胞周期蛋白D1的表达。
Epithelial tight junctions participate in the regulation of gene expression by controlling the activity of transcription factors that can interact with junctional components. One such protein is the Y-box transcription factor ZONAB/DbpA that binds to ZO-1, a component of the junctional plaque. Symplekin, another nuclear protein that can associate with tight junctions, functions in the regulation of polyadenylation and thereby promotes gene expression. Here, we addressed the question of whether these two proteins interact and whether this is of functional relevance. We demonstrate that ZONAB/DbpA and symplekin form a complex in kidney and intestinal epithelial cells that can be immunoprecipitated and that exists in the nucleus. The interaction between ZONAB/DbpA and symplekin can be reconstituted with recombinant proteins. In reporter gene assays in which ZONAB/DbpA functions as a repressor, symplekin functionally interacts with ZONAB/DbpA, indicating that symplekin can also promote transcriptional repression. RNAi experiments indicate that symplekin depletion reduces the nuclear accumulation and the transcriptional activity of ZONAB/DbpA in colon adenocarcinoma cells, resulting in inhibition of proliferation and reduced expression of the ZONAB/DbpA-target gene cyclin D1. Our data thus indicate that symplekin and ZONAB/DbpA cooperate in the regulation of transcription, and that they promote epithelial proliferation and cyclin D1 expression.